What is the model of your computer? Not just dv4000, that is the series. There is a more specific number, like dv4350nr or something.
Use the model number to find out exactly the manufacturer and model of your video card, then google that, or look on HP's website, or look on the manufacturers website.
You will probably find a driver that "works" but does not give you the full features of your video card. Sorry, but unless you want to program your own driver, you are probably out of luck. But follow the steps above anyways just to give it a try.